Chemoresistance Of Cancer Cells Research Articles

Polo-like kinase 2 targeting as novel strategy to sensitize mutant p53-expressing tumor cells to anticancer treatments.

Polo-like kinase 2 (Plk2) belongs to a family of serine/threonine kinases, and it is involved in tumorigenesis of diverse kind of tissues. We previously reported that Plk2 gene was a transcriptional target of the mutant p53/NF-Y oncogenic complex. Plk2 protein can bind to and phosphorylate mutant p53 triggering an oncogenic autoregulatory feedback loop involved in cancer cell proliferation and chemoresistance. In this study, we aimed to assess whether the specific inhibition of Plk2 kinase activity by the selective TC-S 7005 inhibitor could decrease cell proliferation and migration inhibiting mutant p53 phosphorylation, thus disarming its oncogenic potential. We found that the Plk2 inhibitor treatment sensitized the cells to the irradiation and chemotherapy drugs, thereby overcoming the mutant p53-dependent chemoresistance. Taken together, we provided results that Plk2 could be considered a tractable pharmacological target for cancers expressing mutant p53 proteins. The combined treatment with conventional chemotherapeutic drugs and Plk2 inhibitors may represent a new candidate intervention approach, which may be considered for improving tumor cell sensitivity to DNA damaging drugs. KEY MESSAGES : Missense mutations are present in the TP53 gene in about half of all human cancers and correlate with poor patient outcome. Mutant p53 proteins exert gain of function (GOF) activities in tumor cells such as increased proliferation, genomic instability and resistance to therapies. Polo-like kinase 2 (PLK2) binds and phosphorylates mutant p53 protein strengthening its GOF activities. Pharmacologically targeting PLK2 weakens mutant p53 proteins and sensitizes tumor cells to therapeutic treatments.

Receptor for Hyaluronan Mediated Motility (RHAMM)/Hyaluronan Axis in Breast Cancer Chemoresistance

Background/Objectives: Receptor for hyaluronan-mediated motility (RHAMM) is a hyaluronan (HA) receptor, which exerts diverse biological functions in not only physiological but also pathological conditions in human malignancies, including breast cancer. Although chemoresistance is a significant clinical challenge in breast cancer, a possible contribution of RHAMM and hyaluronan to breast cancer chemoresistance has remained unclear. Methods: We immunolocalized RHAMM and HA in breast carcinoma tissues. Also, we utilized epirubicin-sensitive (parental) and rpirubicin-resistant (EPIR) breast cancer cell lines to explore the role of RHAMMM in breast cancer progression. Results: We found out that RHAMM and HA were cooperatively correlated with breast cancer aggressiveness and recurrence after chemotherapy. In vitro studies demonstrated that RHAMM was overexpressed in EPIR cells compared to parental cells. In addition, the knockdown of RHAMM significantly suppressed proliferation and migration of both parental and EPIR cells. On the other hand, the expression level of cancer stem cell marker CD44, which was overexpressed in M-EPIR (epirubicin-resistant MCF-7 subline) compared to MCF-7, was significantly suppressed by knockdown of RHAMM. In addition, the knockdown of RHAMM significantly altered the expression of N-cadherin and E-cadherin, leading to an epithelial phenotype. Conclusions: Aberrant RHAMM signaling were considered to cause chemoresistance related to cancer stemness and epithelial to mesenchymal transition, and increased cell proliferation and migration of both chemo-sensitive and chemo-resistant breast cancer cells.

BATF2 inhibits the stem cell-like properties and chemoresistance of gastric cancer cells through PTEN/AKT/β-catenin pathway

BATF2 inhibits the stem cell-like properties and chemoresistance of gastric cancer cells through PTEN/AKT/β-catenin pathway

Astragalus membranaceus: A Traditional Chinese Medicine with Multifaceted Impacts on Breast Cancer Treatment

Breast cancer, the most prevalent malignant tumor among women globally, remains a critical area of focus for researchers striving to refine therapeutic approaches. As an important component of traditional Chinese medicine, Astragalus membranaceus (AM) has demonstrated potential for multifaceted impacts on breast cancer treatment through various mechanisms. To guide clinical practice and further explore the under-researched field of AM in breast cancer treatment, this paper mainly reviews the regulatory roles of AM-derived compounds and extracts on breast cancer cell proliferation, migration, invasion, and chemoresistance. Furthermore, this study delves into the synergistic effects observed when AM is co-administered with chemotherapeutic agents, including the enhancement of chemosensitivity, mitigation of toxic side effects, and reversal of drug resistance. This review indicates that AM holds promise not only as a therapy in breast cancer treatment but also paves the way for innovative integrated treatment approaches that combine the benefits of traditional medicine with modern pharmaceuticals. Nevertheless, future research endeavors are also urged to elucidate the in vivo pharmacological effects and underlying mechanisms of AM to inform more effective clinical treatment strategies.

Matrine alkaloids modulating DNA damage repair in chemoresistant non-small cell lung cancer cells

BackgroundNon-small cell lung cancer (NSCLC) presents a significant challenge in the medical field due to its high incidence and resistance to chemotherapy. Chemoresistance in NSCLC diminishes treatment efficacy and contributes to poor patient outcomes. Matrine alkaloids have shown promise in reversing chemotherapy resistance in NSCLC by targeting DNA repair mechanisms.MethodsUtilizing molecular dynamics simulations, we explored the interactions between Matrine alkaloids and DNA repair-related proteins to elucidate their impact on NSCLC cells. In vitro experiments involved treating A549/DDP cells with Matrine alkaloids to evaluate their sensitizing effects on lung cancer cells. Additionally, animal model experiments were conducted to validate the therapeutic potential of Matrine alkaloids in NSCLC treatment.ResultsOur findings demonstrate that Matrine alkaloids disrupt DNA damage repair processes in NSCLC cells, leading to increased sensitivity to chemotherapy. Molecular docking studies revealed the intricate mechanisms by which Matrine alkaloids interact with DNA repair proteins, impacting cell survival and proliferation. Both cell experiments and animal models confirmed the chemosensitizing effects of Matrine alkaloids in NSCLC treatment.ConclusionMatrine alkaloids offer a promising avenue for overcoming chemotherapy resistance in NSCLC by interfering with DNA repair pathways. This study lays a solid foundation for future clinical investigations into the potential of Matrine alkaloids as effective therapeutic agents for enhancing NSCLC treatment outcomes.

Tumor-associated macrophages/C-X-C motif chemokine ligand 1 promotes breast cancer autophagy-mediated chemoresistance via IGF1R/STAT3/HMGB1 signaling

Autophagy-mediated chemoresistance is the core mechanism for therapeutic failure and poor prognosis in breast cancer. Breast cancer chemotherapy resistance is believed to be influenced by tumor-associated macrophages (TAMs), by which C-X-C motif chemokine ligand 1 (CXCL1) is the most abundant cytokine secreted. Yet, its role in mediating autophagy-related chemoresistance is still unknown. This study aimed to explore the molecular mechanisms by which TAMs/CXCL1 induced autophagy-mediated chemoresistance in breast cancer. It was found that TAMs/CXCL1 promoted chemoresistance of breast cancer cells through autophagy activation in vitro, and CXCL1 silence could enhance the chemosensitivity of paclitaxel-resistant breast cancer cells via autophagy inhibition. A high-throughput quantitative PCR chip and subsequent target validation showed that CXCL1 induced autophagy-mediated chemoresistance by inhibiting VHL-mediated IGF1R ubiquitination. The elevated IGF1R then promoted STAT3/HMGB1 signaling to facilitate autophagy. Additionally, TAMs/CXCL1 silence improved paclitaxel chemosensitivity by suppressing autophagy in breast cancer mice xenografts, and clinical studies further linked CXCL1 to IGF1R/HMGB1 signaling, as well as shorter free survival of recurrence. Taken together, these results not only uncover the crucial role of TAMs/CXCL1 signaling in mediating breast cancer chemoresistance through enhancing autophagy, but also shed novel light on the molecular mechanism of IGF1R/STAT3/HMGB1 pathway in regulating autophagy and its impact on cancer prognosis.

8817 IGF-II Regulates Magmas A Mitochondrial Protein Required For Cell Viability And ROS Protection

Abstract Disclosure: K. Granados: None. A. Durán: None. F. Almaguel: None. D. De Leon: None. Our laboratory previously showed that Insulin-like growth factor II (IGF-II) promotes cell proliferation, inhibits apoptosis and induces chemoresistance of Breast Cancer (BC) cells. We demonstrated that IGF-II achieves this by inhibiting pro-apoptotic proteins and stimulating anti-apoptotic proteins. Those studies also demonstrated that IGF-II prevented mitochondrial induced apoptosis by inhibiting depolarization of the mitochondrial membrane. Thus, IGF-II regulates the mitochondria to prevent cell death and to promote tumor growth and chemoresistance. Since IGF-II regulates mitochondrial proteins, we decided to assess how IGF-II regulates MAGMAS, a protein located in the inner mitochondrial membrane that is a critical component of a complex that controls mitochondrial protein import and ROS. Of note, MAGMAS was recently identified as being highly expressed in breast cancer, prostate cancer and during early fetal development which parallels IGF-II expression. Immunostaining of TNBC showed high levels of IGF-II and MAGMAS. Thus, our hypothesis is that IGF-II regulates MAGMAS and IGF-II secreting breast cancer cells will express higher levels of MAGMAS. Our preliminary results of rtPCR and Western blotting experiments validated our hypothesis demonstrating that IGF-II regulated the transcription of MAGMAS. To characterize the mechanisms by which IGF-II regulates MAGMAS, we chose the triple negative breast cancer (TNBC) cell line CRL-2335 which we demonstrated produces high levels of IGF-II and MAGMAS. CRL2335 cells were established from an AA TNBC patient and they express high levels of IGF-II and MAGMAS. Confocal microscopy and Western blotting and cellular fractionation were used to assess IGF-II regulation of MAGMAS in TNBC cells. The expression of MAGMAS was analyzed in wild CRL-2335, and IGF-II antisense transfected CRL-2335 cells and compared to cells treated with IGF-II. Results showed that CRL-2335 express high levels of MAGMAS in the mitochondria and blocking the expression of IGF-II by antisense technology significantly decreased MAGMAS. Exogenous IGF-II treatment to the antisense cells increased MAGMAS as demonstrated by Immunofluorescence and WB. Since IGF-II increases the localization of MAGMAS to the mitochondria we propose that IGF-II regulates MAGMAS to protect cancer cells from ROS induced cell death and chemoresistance. Completion of this study will validate IGF-II as a regulator of MAGMAS. Validation of IGF-II regulation of MAGMAS represents an important new tool for the treatment of TNBC. Presentation: 6/2/2024

Hydrazide-Based Class I Selective HDAC Inhibitors Completely Reverse Chemoresistance Synergistically in Platinum-Resistant Solid Cancer Cells.

In this work, we have synthesized a set of peptoid-based histone deacetylase inhibitors (HDACi) with a substituted hydrazide moiety as zinc-binding group. Subsequently, all compounds were evaluated in biochemical HDAC inhibition assays and for their antiproliferative activity against native and cisplatin-resistant cancer cell lines. The hydrazide derivatives with a propyl or butyl substituent (compounds 5 and 6) emerged as the most potent class I HDAC selective inhibitors (HDAC1-3). Further, compounds 5 and 6 outperformed entinostat in cytotoxicity assays and were able to reverse chemoresistance in cisplatin-resistant A2780 (ovarian) and Cal27 (head-neck) cancer cell lines. Moreover, the hydrazide derivatives 5 and 6 showed strong synergism with cisplatin (combination indices <0.2), again outperforming entinostat, and increased DNA damage, p21, and pro-apoptotic BIM expression, leading to caspase-mediated apoptosis and cell death. Thus, compounds 5 and 6 represent promising lead structures for developing new HDACi capable of reversing chemoresistance in cisplatin resistant cancer cells.

Potential Oncogenic and Immunosuppressive Roles of Multiple EGF-Like Domains 6 (MEGF6) in Colon Cancer: Insights from Bioinformatic Analysis

Multiple epidermal growth factor-like domains protein 6 (MEGF6) is a high molecular weight protein with several EGF-like domains. Although it has been demonstrated to promote metastasis and chemoresistance in colon cancer cells, its specific oncogenic and immunologic functions remain largely unexplored. This study aims to comprehensively analyze publicly available datasets to define the role of MEGF6 in colon cancer development and immune response modulation. The expression of MEGF6 in colon adenocarcinoma (COAD) and normal tissues at both mRNA and protein levels was assessed using the GEPIA2 and HPA databases, respectively. The UALCAN database was employed to examine the association between MEGF6 expression and clinicopathological outcomes in COAD patients, and survival analysis was conducted using the KM plotter database. Functional enrichment analysis of MEGF6-correlated genes was performed using the ShinyGO online tool. Additionally, the correlation of MEGF6 with immune cell infiltration and immunosuppressive molecules was explored through the TIMER and TISIDB databases. Our analysis revealed significantly higher mRNA and protein expressions of MEGF6 in COAD tissues compared to normal tissues, with associations to cancer stage, nodal metastasis status, and histological subtype. High MEGF6 expression was correlated with poorer survival outcomes, and genes correlated with MEGF6 were enriched in biological processes related to cellular component organization, cell adhesion, and extracellular matrix interaction. Furthermore, MEGF6 expression demonstrated a significant correlation with immune cell infiltration and the expression of immunosuppressive molecules, particularly CTLA-4, PD-1, PD-L1, TGF-β, and IL-10. In conclusion, our findings suggest that MEGF6 may play an oncogenic role by influencing cell and extracellular matrix interactions. Its overexpression may indicate immunosuppressive properties within the cancer microenvironment. Therefore, MEGF6 holds promise as a potential biomarker for predicting both prognosis and therapeutic responses in colon cancer. HIGHLIGHTS MEGF6 has been shown to involve colon cancer growth and chemotherapeutic resistance. Bioinformatics confirmed a prognostic significance of MEGF6 in colon cancer. MEGF6 may exert its oncogenic effects by influencing cell-matrix interactions. MEGF6 expression is correlated with immunosuppressive properties of cancers. GRAPHICAL ABSTRACT

Identification of Potential Inhibitors for Poly(ADP‐ribose) Polymerase‐10 (PARP10): Virtual Screening, Molecular Docking, and Molecular Dynamics Simulations

AbstractPoly(ADP‐ribose) polymerase‐10 (PARP10) is a critical enzyme involved in DNA damage repair. Its function in cellular repair mechanisms has been implicated in the development of chemoresistance and radioresistance in cancer cells. Consequently, PARP10 inhibition represents a promising, albeit challenging, and therapeutic target for various cancer types. This study aims to discover new PARP10 potential inhibitors via a hybrid of in silico approaches. Initially, pharmacophore‐based virtual screening was conducted on the ZINC and NCI databases. The resulting compounds were subsequently subjected to molecular docking studies to identify potential new PARP10 inhibitors. Subsequently, classical molecular dynamics (MD) simulations were conducted to evaluate and compare the dynamic behavior of the selected ligand, veliparib, and OUL35, a selective PARP10 inhibitor. Ultimately, compound ZINC20906412 was found as a potential lead compound based on its docking score and favorable interactions within the PARP10 active site. This compound may offer therapeutic potential for cancer treatment.

Milk-Derived Exosomes: Innovative Nanocarriers for Enhanced Anticancer Drug Delivery

This in-depth review examines the recently emerging field of using exosomes from milk as anticancer medication nanocarriers. It gives a summary of the most current developments, difficulties, and opportunities in this cutting-edge therapeutic strategy. Exosomes are found in many different body fluids and are considered a promising option for precision medicine due to their biocompatibility and innate cell-targeting abilities. These extracellular vesicles are nanoscale. The review commences with a comprehensive synopsis of the composition and biogenesis of exosomes derived from milk, highlighting their distinct membrane properties and capacity to transport cargo. Interestingly, these naturally occurring nanocarriers hold a variety of bioactive substances that can be precisely delivered as anticancer medications. These substances include proteins, lipids, and nucleic acids. Because dietary(poly) phenols are rapidly metabolized, their ability to prevent cancer is limited. Extracellular vesicles called exosomes may shield polyphenols from metabolism. Our objective was to evaluate the anticancer effects of free curcumin and resveratrol in breast cancer cell lines compared to their encapsulation in extracellular matrix derived from milk. Breast tissue was disposed of kinetically using rats. Curcumin and resveratrol were assessed using UPLC-QTOF-MS and GV-MS, respectively. Dietary polyphenols have a limited capacity to prevent cancer due to their rapid metabolism. Extracellular vesicles called exosomes may shield polyphenols from metabolism. Our goal was to assess in breast tissue. UPLC-QTOF-MS and GV-MS were used to evaluate curcumin and resveratrol, respectively. Curcumin and Resveratrol anticancer activity and bioavailability were improved by milk extracellular urea, which served as Trojan horses to get around the ABC-mediated chemoresistance of cancer cells. Exosomes derived from milk are being studied for their potential as carriers of therapeutic and diagnostic agents, emphasizing the potential benefits of personalized and precision medicine approaches to cancer treatment. The review also covers the challenges that the clinical translation of milk-derived exosome-based drug delivery systems currently faces, including scalability, standardization and safety profiles. The article's conclusion presents an optimistic view of how milk-derived exosomes will develop in the future in terms of anticancer medication delivery. The review highlights the revolutionary potential of using milk-derived exosomes, nature's nanocarriers, to advance the field toward more precise and effective cancer treatments, anticipating future advancements and emerging trends.

Potential of NRF2 Inhibitors-Retinoic Acid, K67, and ML-385-In Overcoming Doxorubicin Resistance in Promyelocytic Leukemia Cells.

Drug resistance is one of the major obstacles to the clinical use of doxorubicin, an extensively used chemotherapeutic drug to treat various cancers, including leukemia. Inhibition of the nuclear factor erythroid 2-related factor 2 (NRF2) seems a promising strategy to reverse chemoresistance in cancer cells. NRF2 is a transcription factor that regulates both antioxidant defense and drug detoxification mechanisms. In this study, we investigated the potential of three inhibitors of NRF2-K67, retinoic acid and ML-385-to overcome doxorubicin resistance in promyelocytic leukemia HL-60 cells. For this purpose, low-dose doxorubicin was used to establish doxorubicin-resistant HL-60/DR cells. The expression of NRF2 and its main repressor, Kelch-like ECH-associated protein 1 (KEAP1), at mRNA and protein levels was examined. HL-60/DR cells overexpressed NRF2 at mRNA and protein levels and down-regulated KEAP1 protein compared to drug-sensitive HL-60 cells. The effects of NRF2 inhibitors on doxorubicin-resistant HL-60/DR cell viability, apoptosis, and intracellular reactive oxygen species (ROS) levels were analyzed. We observed that NRF2 inhibitors significantly sensitized doxorubicin-resistant HL-60/DR cells to doxorubicin, which was associated with increased intracellular ROS levels and the expression of CAS-9, suggesting the participation of the mitochondrial-dependent apoptosis pathway. Furthermore, ML-385 inhibitor was used to study the expression of NRF2-KEAP1 pathway genes. NRF2 gene and protein expression remained unchanged; however, we noted the down-regulation of KEAP1 protein upon ML-385 treatment. Additionally, the expression of NRF2-regulated antioxidant and detoxification genes including SOD2, HMOX2, and GSS was maintained upon ML-385 treatment. In conclusion, our results demonstrated that all the studied inhibitors, namely K67, retinoic acid, and ML-385, increased the efficacy of doxorubicin in doxorubicin-resistant HL-60/DR cells, and suggested a potential strategy of combination therapy using NRF2 inhibitors and doxorubicin in overcoming doxorubicin resistance in leukemia.

TRF-Leu reverse breast cancer cells chemoresistance by regulation of BIRC5

ObjectiveAccumulating studies reported the crucial roles of tRFs in tumorigenesis. However, their further mechanisms and clinical values remains unclear. This study aimed at the further investigation of tRF-Leu in breast cancer chemotherapy resistance.MethodsThe high-throughput sequencing was performed and identified the downregulation of tRF-Leu in MCF7/ADR cells. The function of tRF-Leu in breast cancer cells and breast cancer chemotherapy resistance was investigated in vitro and in vivo, including colony formation assay, CCK-8 assay, transwell assay and apoptosis assay. The binding site of tRF-Leu on BIRC5 was verified by dual-luciferase assay.ResultstRF-Leu was downregulated in MCF7/ADR cells. Overexpression of tRF-Leu inhibited the migration of breast cancer cells. Furthermore, tRF-Leu could reverse the resistance of MCF7/ADR cells to Adriamycin both in vitro and in vivo. BIRC5 was a target of tRF-Leu, which might be involved in the chemotherapy resistance regulation.ConclusionWe demonstrated that tRF-Leu could inhibit the chemotherapy resistance of breast cancer by targeting BIRC5. These findings might identify new biomarkers of breast cancer therapy and bring new strategies to reverse chemotherapy resistance.

SNHG14 promotes triple-negative breast cancer cell proliferation, invasion, and chemoresistance by regulating the ERK/MAPK signaling pathway.

The functional role and molecular mechanisms of small-nucleolar RNA host gene 14 (SNHG14) in triple-negative breast cancer (TNBC) progression remain unclear. The expression levels of SNHG14 in breast cancer samples and cell lines were determined using real-time quantitative polymerase chain reaction. Cell proliferation, migration, and invasion abilities were detected using MTS and transwell assays. By RNA sequencing, differentially expressed genes were identified between the SNHG14 siRNA and the negative control group. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were used to predict the targets and pathways regulated by SNHG14. pRAF, pMEK, and pERK expression were measured by western blot. The xenograft model was constructed to access the biological function of SNHG14 in vivo. A minimal patient-derived xenograft model was established to evaluate the sensitivity to chemotherapy drugs. Our data indicated that SNHG14 expression was increased in TNBC tissues and cell lines. SNHG14 knockdown attenuated the proliferation, migration, and invasion abilities of TNBC cells both in vivo and in vitro. High SNHG14 expression was associated with lymph node metastasis and a high Ki67 index. The targets of SNHG14 were mainly enriched in the MAPK signaling pathway. pRAF, pMEK, and pERK expression were downregulated after being transfected with SNHG14 siRNA. Compared with the negative control group, the expression of CACNA1I, DUSP8, FGF17, FGFR4, FOS, PDGFRB, and DDIT3 was increased, and the expression of MKNK1 was decreased in the SNHG14 siRNA group. Minimal patient-derived xenograft model demonstrated that knockdown of SNHG14 enhanced the sensitivity to Docetaxel in vivo. Compared with the DMSO group, the proliferation of Docetaxel-resistant MDA-MB-231 cells was decreased in Dabrafenib, PD184352, and FR180204 treatment groups. SNHG14 knockdown inhibits TNBC progression by regulating the ERK/MAPK signaling pathway, which provides evidence for SNHG14 as a potential target for TNBC therapy.

TCEB2/HIF1A signaling axis promotes chemoresistance in ovarian cancer cells by enhancing glycolysis and angiogenesis

Ovarian cancer is an extremely malignant gynaecological tumour with a poor patient prognosis and is often associated with chemoresistance. Thus, exploring new therapeutic approaches to improving tumour chemosensitivity is important. The expression of transcription elongation factor B polypeptide 2 (TCEB2) gene is reportedly upregulated in ovarian cancer tumour tissues with acquired resistance, but the specific mechanism involved in tumour resistance remains unclear. In this study, we found that TCEB2 was abnormally highly expressed in cisplatin-resistant tumour tissues and cells. TCEB2 silencing also inhibited the growth and glycolysis of SKOV-3/cisplatin (DDP) and A2780/DDP cells. We further incubated human umbilical vein endothelial cells (HUVECs) with culture supernatants from cisplatin-resistant cells having TCEB2 knockdown. Results revealed that the migration, invasion, and angiogenesis of HUVECs were significantly inhibited. Online bioinformatics analysis revealed that the hypoxia-inducible factor-1A (HIF-1A) protein may bind to TCEB2, and TCEB2 silencing inhibited SKOV-3/DDP cell growth and glycolysis by downregulating HIF1A expression. Similarly, TCEB2 promoted HUVEC migration, invasion, and angiogenesis by upregulating HIF1A expression. In vivo experiments showed that TCEB2 silencing enhanced the sensitivity of ovarian cancer nude mice to cisplatin and that TCEB2 knockdown inhibited the glycolysis and angiogenesis of tumour cells. Our findings can serve as a reference for treating chemoresistant ovarian cancer.

WTAP weakens oxaliplatin chemosensitivity of colorectal cancer by preventing PANoptosis

As the most abundant post-transcriptional modification in eukaryotes, N6-methyladenosine (m6A) plays a crucial role in cancer cell proliferation, invasion and chemoresistance. However, its specific effects on chemosensitivity to oxaliplatin-based regimens and the impact of these drugs on m6A methylation levels in colorectal cancer (CRC) remain largely unexplored. In this study, we demonstrated that the m6A methyltransferase Wilms tumor 1-associating protein (WTAP) weakens oxaliplatin chemosensitivity in HCT116 and DLD1 cells. Mechanistically, oxaliplatin treatment upregulated WTAP expression, preventing multiple forms of cell death simultaneously, a process known as PANoptosis, by decreasing intracellular oxidative stress through maintaining the expression of nuclear factor erythroid-2-related factor 2 (NRF2), a major antioxidant response element, in an m6A-dependent manner. In addition, high WTAP expression in CRC patients is associated with a poor prognosis and reduced benefit from standard chemotherapy by clinical data analysis of The Cancer Genome Atlas (TCGA) database and patient cohort study. These findings suggest that targeting WTAP-NRF2-PANoptosis axis could enhance the antitumor efficacy of oxaliplatin-based chemotherapy in CRC treatment.

NEK6 dampens FOXO3 nuclear translocation to stabilize C-MYC and promotes subsequent de novo purine synthesis to support ovarian cancer chemoresistance

De novo purine synthesis metabolism plays a crucial role in tumor cell survival and malignant progression. However, the specific impact of this metabolic pathway on chemoresistance in ovarian cancer remains unclear. This study aims to elucidate the influence of de novo purine synthesis on chemoresistance in ovarian cancer and its underlying regulatory mechanisms. We analyzed metabolic differences between chemosensitive and chemoresistant ovarian cancer tissues using mass spectrometry-based metabolomics. Cell growth, metabolism, chemoresistance, and DNA damage repair characteristics were assessed in vitro using cell line models. Tumor growth and chemoresistance were assessed in vivo using ovarian cancer xenograft tumors. Intervention of purines and NEK6-mediated purine metabolism on chemoresistance was investigated at multiple levels. Chemoresistant ovarian cancers exhibited higher purine abundance and NEK6 expression. Inhibiting NEK6 led to decreased de novo purine synthesis, resulting in diminished chemoresistance in ovarian cancer cells. Mechanistically, NEK6 directly interacted with FOXO3, contributing to the phosphorylation of FOXO3 at S7 through its kinase activity, thereby inhibiting its nuclear translocation. Nuclear FOXO3 promoted FBXW7 transcription, leading to c-MYC ubiquitination and suppression of de novo purine synthesis. Paeonol, by inhibiting NEK6, suppressed de novo purine synthesis and enhanced chemosensitivity. The NEK6-mediated reprogramming of de novo purine synthesis emerges as a critical pathway influencing chemoresistance in ovarian cancer. Paeonol exhibits the potential to interfere with NEK6, thereby inhibiting chemoresistance.

IRE1α-XBP1s axis regulates SREBP1-dependent MRP1 expression to promote chemoresistance in non-small cell lung cancer cells.

Inositol-requiring enzyme 1 (IRE1) is an endoplasmic reticulum (ER)-resident transmembrane protein that senses ER stress and mediates an essential arm of the unfolded protein response (UPR). IRE1 reduces ER stress by upregulating the expression of multiple ER chaperones through activation of X-box-binding protein 1 (XBP1). Emerging lines of evidence have revealed that IRE1-XBP1 axis serves as a multipurpose signal transducer during oncogenic transformation and cancer development. In this study, we explore how IRE1-XBP1 signaling promotes chemoresistance in lung cancer. The expression patterns of UPR components and MRP1 were examined by Western blot. qRT-PCR was employed to determine RNA expression. The promoter activity was determined by luciferase reporter assay. Chemoresistant cancer cells were analyzed by viability, apoptosis. CUT & Tag (Cleavage under targets and tagmentation)-qPCR analysis was used for analysis of DNA-protein interaction. Here we show that activation of IRE1α-XBP1 pathway leads to an increase in MDR-related protein 1 (MRP1) expression, which facilitates drug extrusion and confers resistance to cytotoxic chemotherapy. At the molecular level, XBP1-induced c-Myc is necessary for SREBP1 expression, and SREBP1 binds to the MRP1 promoter to directly regulate its transcription. We conclude that IRE1α-XBP1 had important role in chemoresistance and appears to be a novel prognostic marker for lung cancer.

KLF1 Activates RAC3 to Mediate Fatty Acid Synthesis and Enhance Cisplatin Resistance in Bladder Cancer Cells.

While cisplatin remains a frontline treatment for bladder cancer (BCa), the onset of resistance greatly hampers its effectiveness. RAC3 is closely linked to chemoresistance in cancer cells, but its specific role in cisplatin resistance within BCa is still elusive. RAC3 expression in BCa was analyzed using bioinformatics and quantitative polymerase chain reaction (qPCR). The gene set enrichment analysis (GSEA) identified RAC3-enriched pathways and the correlation between RAC3 and fatty acid synthase (FASN), a gene involved in fatty acid synthesis. Potential upstream transcription factors of RAC3 were predicted and their interaction with RAC3 was confirmed via dual-luciferase and chromatin immunoprecipitation (ChIP) assays. T24/DDP, a cisplatin-resistant BCa cell line, was established to probe into the regulatory role of RAC3 in cisplatin resistance. Cell proliferation was evaluated by colony formation and the IC50 values after cisplatin treatment were determined using cell counting kit-8 (CCK-8). The levels of free fatty acids and triglycerides (TGs), as well as the expression of DGAT2 and FASN proteins, were measured to gauge the extent of fatty acid synthesis in cells. Elevated expression of RAC3 was observed in BCa and the cisplatin-resistant BCa cells (T24/DDP). The knockdown of RAC3 within T24/DDP cells was demonstrated to counteract cisplatin resistance. Subsequent analyses identified RAC3 as being notably enriched in the fatty acid synthesis pathway, with Kruppel-like factor 1 (KLF1) emerging as a key upstream regulator. The overexpression of RAC3 was correlated with increased cisplatin resistance in T24/DDP cells, an effect that was mitigated by the addition of the FASN inhibitor, Orlistat. Furthermore, the downregulation of KLF1 suppressed RAC3 expression, disrupted fatty acid synthesis, and attenuated cisplatin resistance in T24/DDP cells. Conversely, the co-overexpression of RAC3 counteracted the effects conferred by KLF1 knockdown. Our study has validated that KLF1 activates RAC3 to mediate fatty acid synthesis and promote cisplatin resistance in BCa, suggesting the KLF1/RAC3 axis as a potential target for combating cisplatin-resistant BCa.

A novel lipophilic amiloride derivative efficiently kills chemoresistant breast cancer cells

Derivatives of the potassium-sparing diuretic amiloride are preferentially cytotoxic toward tumor cells relative to normal cells, and have the capacity to target tumor cell populations resistant to currently employed therapeutic agents. However, a major barrier to clinical translation of the amilorides is their modest cytotoxic potency, with estimated IC50 values in the high micromolar range. Here we report the synthesis of ten novel amiloride derivatives and the characterization of their cytotoxic potency toward MCF7 (ER/PR-positive), SKBR3 (HER2-positive) and MDA-MB-231 (triple negative) cell line models of breast cancer. Comparisons of derivative structure with cytotoxic potency toward these cell lines underscore the importance of an intact guanidine group, and uncover a strong link between drug-induced cytotoxicity and drug lipophilicity. We demonstrate that our most potent derivative called LLC1 is preferentially cytotoxic toward mouse mammary tumor over normal epithelial organoids, acts in the single digit micromolar range on breast cancer cell line models representing all major subtypes, acts on cell lines that exhibit both transient and sustained resistance to chemotherapeutic agents, but exhibits limited anti-tumor effects in a mouse model of metastatic breast cancer. Nonetheless, our observations offer a roadmap for the future optimization of amiloride-based compounds with preferential cytotoxicity toward breast tumor cells.